Aspirator Needle

Abstract

An aspirator needle for use in open-heart surgery during cardiopulmonary bypass to reduce the risk of air entrapment in the aorta. The needle consists of a cannula provided with a pointed end and an axial slot in the wall thereof extending substantially the length of the cannula, and a hub configured to connect to a source of suction via a connecting tube.

Description

BACKGROUND OF THE INVENTION

This invention relates to medical devices, and more particularly to a disposable aspirator needle for use in eliminating air embolism during cardiopulmonary bypass procedures.

In an article entitled "A Needle-Vent Safeguard Against Systemic Air Embolus in Open-Heart Surgery," written by Doctors L.K. Groves and D.B. Effler for the Department of Thoracic Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio, the dangers of entrapment of air in the left side of the heart, which may then enter the systemic circulation, is discussed in great detail. Briefly, as this article points out, in most open-heart procedures the highest point in the central cardiovascular system is the ascending aortic arch between the aortic valve ring and the innominate artery takeoff, and that any air accumulating in the circulatory system during an operative procedure will of necessity flow along the upper surface of the aorta and form a bubble at this highest point. An air bubble that reaches this aortic arch may enter the innominate artery and thus gain access to the right carotid artery circulation and cause neurologic deficits in the left half of the body.

While air or other gases may also accumulate in other portions of the cardiovascular system adjacent the heart during cardiopulmonary bypass, and while considerable quantities of air can frequently be tolerated in the systemic circulation without causing obvious complications, it is well known that a minute embolus carried to a strategic location may cause tragic consequences.

While the above article describes a vent needle suitable for use in removing air entrapped in the aortic arch, and while many issued patents, such as U.S. Pat. No. 3,076,457, disclose aspirating needles which may possibly be used for this purpose, none of these prior art devices have proven entirely satisfactory for the purposes hereinbefore described.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an aspirator needle which permits rapid and effective aspiration of air trapped in the cardiovascular system during cardiopulmonary bypass procedures.

It is another object of this invention to provide such an aspirating needle which substantially eliminates the disadvantages of prior art devices, and which is characterized by simplicity of construction, and ease of operation and use.

A still further object of this invention is to provide such a needle which is of economical construction for disposal after but a single use, but which is highly effective and safe.

An aspirator needle constructed in accordance with the present invention is comprised of a needle cannula having a point at its distal end and an elongate slot extending axially through tbe wall of the cannula over substantially the entire length thereof. A hub, having an axial bore therein, is provided with a distal end portion receiving the butt end of the needle cannula in fluid flow communication with the bore of the hub. The hub further comprises an elongate generally cylindrical center portion and a proximal end portion, the latter having means thereon for detachably receiving a flexible tube over the periphery of the proximal end portion of the hub.

These and other objects and features will be in part apparent and in part pointed out hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal view of the aspirator needle of this invention;

FIG. 2 is an enlarged transverse sectional view taken on lines 2--2 of FIG. 1; and

FIG. 3 is a diagramatic view of the aspirator needle of this invention as it is used.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, and particularly to FIG. 1, the present aspirator needle, generally indicated at 10, is shown to comprise a needle cannula 12 and a hub 14. The needle cannula 12 is of elongate, cylindrical configuration having a bevel point 16 at its distal end and an elongate slot 18 extending axially through the wall of the cannula over substantially the entire length thereof. As illustrated in FIG. 1 of the drawings, the slot 18 terminates at the butt end 20 of the needle just short of the hub 14, and is embedded in the hub and attached thereto by any suitable means, such as by an epoxy adhesive.

The hub 14 is comprised of a cylindrical distal end portion 22, an elongate center portion 24 and a proximal end portion 25. As illustrated in the drawings, center section 24 is provided with four axially extending ribs 27 to assist in grasping the needle, and proximal end portion 25 is provided with three peripherally extending circular tube retaining ridges 26, each of which tapers from a maximum diameter at its distal end to a minimum diameter at its proximal end substantially coextensive with the surface of the proximal end portion 25 of the hub. While three such tube retaining ridges have been illustrated and described, it should be understood that any suitable number may be provided for securing the tube to the proximal end portion of the needle hub 14. The hub 14 is further provided with substantially planar proximal and distal end faces 28 and 30, respectively. In addition, a peripherally extending enlarged diameter shoulder 32 is provided on the needle hub intermediate the center and proximal end portions thereof which serves as a tube stop, as will be described more fully hereinafter. As illustrated by dotted lines 34 in FIG. 1, the hub has a tapering axial bore extending throughout its length in fluid flow communication with the butt end 20 of needle cannula 12. The proximal end of the bore 34 is open at face 28 of the hub.

The needle cannula 12 and hub 14 are preferably formed of stainless steel and a suitable synthetic resinous material such as polypropylene, respectively, to provide an assembly of low cost so that the aspirator needle may be disposed of after a single use. As illustrated in FIG. 1, the aspirator needle is preferably 21/2 inches in overall length with the hub portion 14 extending approximately 2 inches and the free length of the needle cannula extending from the distal face 30 of the hub approximately 1/2 inch. This provides an assembly which is easily manipulated for insertion and retraction of the needle cannula through the wall of the aorta, or other body vessel, without extending completely through both walls of the vessel. In addition, the free length of the butt end 20 of the needle cannula 12 is approximately 0.078 inches in axial dimension to ensure that this portion of the needle cannula extends completely through the wall of the aorta to prevent aspiration of the vessel tissues into the slot 18.

As illustrated in FIG. 3 of the drawings, the aspirator needle 10 is detachably connected to a flexible aspirating tube 36 by telescoping the end of the tubing over the proximal end portion 25 of the needle hub into abutment with shoulder 32. The tube retaining ridges 26 securely retain the tube on the proximal end portion of the hub to prevent inadvertent disassembly thereof. With the tube 36 connected to the needle hub portion 25, and with the tubing 36 connected to a suitable aspirating pump or source of negative pressure, the needle cannula 12 is inserted through the wall 38 of the aorta for aspiration of air bubbles, such as those indicated at 40, trapped therein. Since the slot 18 extends over substantially the entire length of the needle cannula 12, all of the air trapped in the aortic arch, including that along the uppermost surface of the aortic wall, will be removed. Furthermore, the slotted needle facilitates removal of air bubbles with a small puncture. In addition, since the butt end 20 of the needle cannula 12 is unslotted, the aortic wall 38 will not be damaged by aspiration into the needle.

Th present needle may be used at the conclusion of cardiopulmonary bypass to reduce the risk of air entrapment in the aorta when going off bypass or continuously throughout the operative procedure, depending on the particular procedure performed by the surgeon. While some blood loss will occur through the needle, depending upon the perfusion pressure used, this blood may be returned to the patient through either the cardiotomy reservoir or the oxygenator.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results obtained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpretted as illustrative and not in a limiting sense.

Claims

What is claimed is:

1. An aspirator needle for insertion into a body vessel comprising a needle cannula having a pointed distal end, and a hub connected to a proximal portion of said cannula and having a distal end face, said cannula having a free portion extending axially from said end face for a distance less than the diameter of the body vessel to prevent penetration of the opposed wall of the body vessel when the aspirator needle is inserted with said end face substantially engaging the exterior of the body vessel, said free portion having an axially elongate slot extending through the wall of said cannula with the proximal end of said slot spaced from said end face to define therebetween an unslotted portion and to define a slotted portion between tbe proximal end of said slot and the distal end of said cannula, said unslotted portion being substantially smaller in axial length than said slotted portion so that when the aspirator needle is inserted into the body vessel substantially up to said end face, the proximal end of said slot is closely adjacent the interior of the body vessel wall so that air bubbles within the body vessel adjacent the interior of the body vessel wall can enter said slot, said hub having a bore therein in fluid communication with said cannula and means thereon for receiving a flexible tube in fluid communication with said bore.

2. The aspirator needle set forth in claim 1 wherein said slot extends continuously from the proximal end of said slot to the distal end of said cannula.

3. The aspirator needle set forth in claim 1 wherein said unslotted portion is cylindrical and has an axial length approximately equal to the average thickness of the body vessel wall.

4. The aspirator needle set forth in claim 3 wherein said slot extends continuously from the proximal end of said slot to the distal end of said cannula.

5. The aspirator needle set forth in claim 1 wherein the axial length of said unslotted portion is approximately .078 inch and the axial length of said slotted portion is approximately .422 inch.

6. The aspirator needle set forth in claim 5 wherein said slot extends continuously from the proximal end of said slot to the distal end of said cannula.

7. The aspirator needle set forth in claim 1 wherein the axial length of said hub is at least two times the length of said free portion of said cannula.